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1   /**
2    * Copyright (c) 2004-2011 QOS.ch
3    * All rights reserved.
4    *
5    * Permission is hereby granted, free  of charge, to any person obtaining
6    * a  copy  of this  software  and  associated  documentation files  (the
7    * "Software"), to  deal in  the Software without  restriction, including
8    * without limitation  the rights to  use, copy, modify,  merge, publish,
9    * distribute,  sublicense, and/or sell  copies of  the Software,  and to
10   * permit persons to whom the Software  is furnished to do so, subject to
11   * the following conditions:
12   *
13   * The  above  copyright  notice  and  this permission  notice  shall  be
14   * included in all copies or substantial portions of the Software.
15   *
16   * THE  SOFTWARE IS  PROVIDED  "AS  IS", WITHOUT  WARRANTY  OF ANY  KIND,
17   * EXPRESS OR  IMPLIED, INCLUDING  BUT NOT LIMITED  TO THE  WARRANTIES OF
18   * MERCHANTABILITY,    FITNESS    FOR    A   PARTICULAR    PURPOSE    AND
19   * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
20   * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
21   * OF CONTRACT, TORT OR OTHERWISE,  ARISING FROM, OUT OF OR IN CONNECTION
22   * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
23   *
24   */
25  package org.slf4j;
26  
27  import java.io.Serializable;
28  import java.util.Iterator;
29  
30  /**
31   * Markers are named objects used to enrich log statements. Conforming logging
32   * system Implementations of SLF4J determine how information conveyed by markers
33   * are used, if at all. In particular, many conforming logging systems ignore
34   * marker data.
35   * 
36   * <p>
37   * Markers can contain references to other markers, which in turn may contain 
38   * references of their own.
39   * 
40   * @author Ceki G&uuml;lc&uuml;
41   */
42  public interface Marker extends Serializable {
43  
44    /**
45     * This constant represents any marker, including a null marker.
46     */
47    public final String ANY_MARKER = "*";
48  
49    /**
50     * This constant represents any non-null marker.
51     */
52    public final String ANY_NON_NULL_MARKER = "+";
53  
54    /**
55     * Get the name of this Marker.
56     * 
57     * @return name of marker
58     */
59    public String getName();
60  
61    /**
62     * Add a reference to another Marker.
63     * 
64     * @param reference
65     *                a reference to another marker
66     * @throws IllegalArgumentException
67     *                 if 'reference' is null
68     */
69    public void add(Marker reference);
70  
71    /**
72     * Remove a marker reference.
73     * 
74     * @param reference
75     *                the marker reference to remove
76     * @return true if reference could be found and removed, false otherwise.
77     */
78    public boolean remove(Marker reference);
79  
80    /**
81     * @deprecated Replaced by {@link #hasReferences()}.
82     */
83    public boolean hasChildren();
84    
85    /**
86     * Does this marker have any references?
87     * 
88     * @return true if this marker has one or more references, false otherwise.
89     */
90    public boolean hasReferences();
91    
92    /**
93     * Returns an Iterator which can be used to iterate over the references of this
94     * marker. An empty iterator is returned when this marker has no references.
95     * 
96     * @return Iterator over the references of this marker
97     */
98    public Iterator<Marker> iterator();
99  
100   /**
101    * Does this marker contain a reference to the 'other' marker? Marker A is defined 
102    * to contain marker B, if A == B or if B is referenced by A, or if B is referenced
103    * by any one of A's references (recursively).
104    * 
105    * @param other
106    *                The marker to test for inclusion.
107    * @throws IllegalArgumentException
108    *                 if 'other' is null
109    * @return Whether this marker contains the other marker.
110    */
111   public boolean contains(Marker other);
112 
113   /**
114    * Does this marker contain the marker named 'name'?
115    * 
116    * If 'name' is null the returned value is always false.
117    * 
118    * @param name The marker name to test for inclusion.
119    * @return Whether this marker contains the other marker.
120    */
121   public boolean contains(String name);
122 
123   /**
124    * Markers are considered equal if they have the same name.
125    *
126    * @param o
127    * @return true, if this.name equals o.name
128    *
129    * @since 1.5.1
130    */
131   public boolean equals(Object o);
132 
133   /**
134    * Compute the hash code based on the name of this marker.
135    * Note that markers are considered equal if they have the same name.
136    * 
137    * @return the computed hashCode
138    * @since 1.5.1
139    */
140   public int hashCode();
141 
142 }